Occlusion shadows: using projected light to generate realistic occlusion effects for view-dependent optical see-through displays

This paper presents projector-based illumination techniques for creating correct occlusion effects for optical see-through setups. We project view-dependent occlusion shadows onto the real surfaces that are located behind virtual objects. This results in a perfect occlusion of real objects by virtual ones. We have implemented and tested our approach in the context of the Virtual Showcase display. We describe a hardware extension for projecting light into the showcase and present our rendering techniques for displaying occlusion shadows for single and multi-user environments as well as for single and multi-light-projector configurations. We also report on the limitations of our system for multi-user situations and describe our experiences with a first experimental prototype.